00.Introduction

    Commercially sterile products have been on the market for a long time. Direct

  UHT (Ultra High Temperature) processing was introduced at the beginning ofthe 20th century. At that time, the technology was used only as a pre-treatmentfor products to be filled into cans for subsequent retorting. The first UHT-treatedand aseptically packaged products were in cans and were shown at an agricultural exhibition in London in the mid 1920s. The product (milk) was not a commercial success. During the early 1930s, aseptic canning was developed in the USA (69).

    In 1961, aseptic packaging procedures were introduced (74, 93, 243) using flexible packaging material (a laminate of wax, paper and polyethylene): theTetra Pak system (“Tetra Classic Aseptic” or TCA system). The paperboardcarton and black colouring provided protection against the entry of light. How-ever, gas barrier characteristics were rather poor. In the meantime, UHT process-ing systems were in more general use. After initial problems, the combination ofUHT processing and aseptic packaging in the TCA system gained market success(“long-life products”).

   In 1969, a brick-shaped package was introduced (“Tetra Brik Aseptic” or TBAsystem). The structure of the packaging material was more complex: a poly-ethylene-paper-polyethylene-aluminium foil-polyethylene laminate. Such amaterial provides protection against the entry of light and acts as an effective gasbarrier. The shape of the container offered considerable advantages in storage,transportation and handling. It also provided the real break through for UHTprocessing and aseptic packaging technology. Today, larger quantities of both low and high-acid, shelf-stable food products are processed by inflow (UHT)methods and subsequently packaged under aseptic conditions. Milk andmilk-based products were the first long-life food products and still remain thelargest commodity in terms of volume.

    Processes that stabilise food thermally have been a major benefit to mankindby providing stability and safety in food. Although commercial canning isprobably the most reliable and safest method of food preservation, it is not perfect. In trying to improve the technology, the present low risk of contamina-tion present in simple straight forward technologies must sometimes be sacrificed to gain better quality and economy.

    Aseptic technology is considered to have the followingadvantages over conventional technologies (254):

    a)new package forms;

    b)savings in energy and packaging costs;

    c)convenience; and

    d)improved product quality.

    A comparison of the price of different packaging alternativesis shown in table 1 (278).In table 2, the total cost of canning is compared to theproduction of a long-life food product (table 2, 179).